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ID Exam 3 A
Ramsinghani Cyclic Peptide Antibiotics
| Question | Answer |
|---|---|
| What are the common features seen in cyclic antibiotics? | they are natural products (some analogs); Peptide bonds; cyclic structure; D-amino acids; Unusual amino acids; more toxic to host than other antibioitcs |
| Vancomycin is a ________ containing a sugar and a peptide sturcutre where 2 sugars are __________ linked to one another. | Glycopeptide; glycocydically linked |
| What 2 sugars are seen in Vancomycine? how many peptide bonds are present in Vancomycin? | Vancosamine and Glucose; 6 |
| What is the MOA of Vancomycin? | inhibition of cell wall synthesis; binds to the D-Ala-D-Ala of NAM-NAG monomer--> inhinitng the polymerization and also prevents the cross linking |
| What 2 enzymes are prevented when using Vancomycin? | transglycosylase and transpeptidase |
| What is the Antibacterial spectrum of Vancomycin? | Gram + only |
| Due to Vancomycin's insufficent oral absorption its given IV, yet its ORAL form can be used for ___ __________ such as Clostridioides difficile overgrowth | GI infections |
| What are the ADR's of Vancomycin? | Vancomycin Infusion rxn (VIR); **Ototoxicity and Nephrotoxicitiy |
| When Vanco is given as a slow infusion, it helps to manage the VIR, what should we use to pre-treat the pt? | antihistamines |
| The Mechanisms of bacterial resistance of Vancomycin is? | Vancomycin Resistant Enterococcus (VRE) |
| VRE is cuased by E. faecium, and E. faecalis which can change the target D-Ala-D-Ala to what? | D-Ala-D-LACTATE or D-Ala-D-SER (this transfer of target will cause poor binding) |
| VRSA (Vancomycin resistant S. Aureus) can occur with a gene transfer from VRE to MRSA, what is the name of this gene? | VanA |
| VISA can occur via intermediated staph aureus which occur when stapf can thicken their ______ _____ where the drug can't get to teh targe easily | cell wall (VISA: cell wall thickening) |
| Vancomycin is mostly used in the hospital setting for treating _____. Vancomycin's half-life and PPB is? | MRSA; 4-6h; 55% |
| What are your semi-synthetic derivatives of Vancomycin? What are their half-lives due to their high Plasma protein binding of (90%)? Due to their PK, these will be dosed ______ _______ | TelaVANcin (6-9h), DalbaVANcin (346h), OritaVANcin (245h); less frequently |
| Telavancin, Dalbavancin, and Oritavancin MOA is? | same as Vancomycin PLUS disruption of cell membrane integrity |
| Vanco is given every? Telavancin is dosed? Dalbavanic and Oritavancin are: | 8-12 hours; once daily single dose |
| Your semi-synthetic vanco derivatives are all active against gram (+), which species? | MSSA, MRSA, VRSA, and VISA |
| Your semi-synthetic vanco's are used to treat? | acute bacterial skin and skin structure infections yet TelaVANcin can be used to treat HAP and VAP |
| Which features of your cyclic peptides are protective of its structure from degradation? | cyclic peptide structurel unusual amino acids D-Amino acids |
| Daptomycin is a cyclic lipopolypeptide containing a lipid tail with 9 carbons. Its MOA is? | binds to cell membranes and causes DEPOLARIZATION (causes a change where K+ can come out causing depolarization) |
| Daptomycin's antibacterial spectrum is for ____ ___ especially for sink and skin structure infection such as _____, _____ | Gram (+); MRSA, VRE |
| Daptomycin has poor oral absorption and is given as a slow IV infusion. Its adverse rxns are: | muscle pain/weakness and increased serum creatinine phosphokinase |
| What Drug interactions can occur with Daptomycin? | HMG-CoA reductase inhibitors leading to an increased risk of skeletal muscle toxicity (Rhabdo) |
| Colistin also known as ______ __ is a CATIONIC antibiotic that binds to the anionic bacterial _____ _______ leading to a disruption of membrane integrity | Polymixin E; OUTER MEMBRANE |
| Colistin (Polymixin E) contains 2 amino groups that can be charged at Physiological pH. Its use is effective against? | Gram (-) bacteria |
| How does collistin bind to gram (-) bacteria? | Their outer membrane is a lipo-polysaccharide rich in phosphates which are negatively charged so the + charged drug will bind to the (-) charge phosphates of the outer membrane |
| Colistin contains DAB which stands for __ _______ _______ _____. its structure contains 2 amnio groups which can be + charged at physiological pH | Di-amino buteric acid |
| Colistin comes in what drug formulations? | Colistimethate Na-->IM injection or as an Oral inhalation **oral inhalation of colistin can be used for CYSTIC FIBROSIS |
| Colistin's antibacterial spectrum is? | active against gram (-) bacilli especially P. aeruginosa *RAMSINGHANI "remember it has the DAB |
| Colisitin is Polymixin E containing DAB which contains D-Leu; however if D-leu converts to D-Phe it becomes: | Polymixin B (Cyclic Lipopeptide) |
| Colistin's main PK's to remember are: | Metabolism: Colistimethate--> Colisitin (Active form) This is where DAB is modified with a Na+); Toxicity: nephrotoxicity; Neuromusclular blockade |
| Drug interactions with Colistin: We see increased nephrotoxicity when Colistin is added with (1) We see increased neuromuscular blockade when Colistin is added with (2) | 1. aminoglycosides; amphotericin B; and Vancomycin 2. with neuromuscular blocking agents i.e. Succinylcholine |
| Mechanism of Bacterial resistance for Colistin can occur via: | changes in the outer lipopolysaccharide layer or phosphate content leading to ---> decreased binding of the drug |
| Bacitracin's MOA is? | interferes with the dephosphorylation of the glycophsopholipid carrier in the cell wall synthesis |
| Ramsinghani wants us to know the antibiotics that make up "TRIPLE ANTIBIOTIC" | Bacitracin Zn Neomycin sulfate Polymixin B sulfate |
| Bacitracin's antibacterial spectrum includes? | activity against gram (+) bacteria |
| Adverse rxns of Bacitracin include: | Neurotoxicity Nephrotoxicity Bone marrow toxicity |
| Due to its toxicity profile, Bacitracin is given? | topically |
| Mupirocin is ______ a cyclic structure. Its a 9-carbon chain lipid structure. | NOT |
| What is Mupirocin's MOA? | bind specificlaly to bacterial ISOLEUCINE (tRNA synthetase)--> preventing incorporation of isoleucine into bacterial proteins for protein synthesis. |
| Mupirocin's antibacterial spectrum includes: | primarily against gram (+) streptococcal and staphylococcal infections with activity against MRSA |
| Mupirocin's PK profile: Absorption: systemic absorption through intact skin and skin lesions is minimal. Its Metabolism when applied to the skin causes what? | rapid hydrolysis to MONIC ACID (hydrolysis at ester group) |
| The mechanism of bacterial resistance with Mupirocin is rare but bacteria can synthesize a BYPASS known as? | Alteration of target "Bypass" synthetase |
| Mupirocin can be used via? | topically and intranasal (nasal MRSA) |
| Which is the only cyclic peptide for gram (-) bacteria? | Colistin (due to containing DAB) |
| Which of your cyclic peptides should NOT be used with other nephrotoxic drugs? | Vancomycin and Colistin; Bacitracin is a topical preparation so we don't have to worry about nephrotoxicity. |
| Key points to remember: Cyclic peptide antibiotics are mostly (1) ____ _____. They have (2)_____ MOA. They are active against gram -positive bacteria, except (3)_____. They possess (4) ____ drug toxicities | 1. natural compounds 2. diverse 3. Colistin 4. unique |
Created by:
Xander635
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